Kiamars Eskandari | Isfahan University of Technology (original) (raw)

Papers by Kiamars Eskandari

Crystal Growth & Design, 2020

A family of 10 compounds, each containing a MX2–pyrazine carboxylate complex anion and a protonat... more A family of 10 compounds, each containing a MX2–pyrazine carboxylate complex anion and a protonated halo– (X′−) amino pyridine cation (MX2 = ZnCl2, ZnBr2, ZnI2, HgBr2, and HgI2; X′ = Cl, Br, I), ar...

Journal of Computational Chemistry

New Journal of Chemistry, 2021

A highly sensitive anthracene–quinoline based dual-mode sensor has been synthesized and used for ... more A highly sensitive anthracene–quinoline based dual-mode sensor has been synthesized and used for the fluorometric and colorimetric detection of Fe3+ and in live cell imaging.

Molecular Physics, 2018

The metal-ligand bonds in the M 2-NH 3 complexes (M = Au, Ag and Cu) are directional and the MM -... more The metal-ligand bonds in the M 2-NH 3 complexes (M = Au, Ag and Cu) are directional and the MM -N angles tend to be linear. Natural energy decomposition analysis (NEDA) and localised molecular orbital energy decomposition analysis (LMOEDA) approaches indicate that the metal-ligand bonds in these complexes are mainly electrostatic in nature, however, the electrostatic is not the cause of the linearity of MM -N arrangements. Instead, NEDA shows that the charge transfer and core repulsion are mainly responsible for the directionality of these bonds. In the LMOEDA point of view, the repulsion term is the main reason for the linearity of these complexes. Interacting quantum atoms (IQA) analysis shows that inter-atomic and inter-fragment interactions favour the nonlinear arrangements; however, these terms are compensated by the atomic self-energies, which stabilise the linear structure.

Materials Today Communications, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2019

A new fluorene based fluorogenic chemosensor, 2-[(9H-Fluoren-2-ylmethylene)-amino]-phenol (L), ha... more A new fluorene based fluorogenic chemosensor, 2-[(9H-Fluoren-2-ylmethylene)-amino]-phenol (L), has been designed, synthesized, and characterized by CHN analyses and different spectroscopic methods. This turn-on fluorogenic chemosensor shows high selectivity and sensitivity toward Cu 2+ and CN¯ with low detection limits of 1.54 × 10-9 M and 1.83 × 10-7 M, respectively. The stoichiometry ratio of L-Cu 2+ in solution is 1:1, by the method of Job's plot and ESI-MS. The microcrystalline solid product of the chemosensor reaction with copper is characterized as CuL 2. The χT value for CuL 2 is temperature independent at a value of 0.403 cm 3 K mol-1 , which is in agreement with a mononuclear copper(II) complex with an isotropic g-value of 2.075. The fluorescence turn-on recognition process for detection of Cu 2+ is attributed to the restricted imine isomerization and blocking of intramolecular charge transfer (ICT) quenching process in the analyte-bound sensor. The selectivity of L for Cu 2+ is based on the chelationenhanced fluorescence effect (CHEF) mechanism. Other interfering ions such as

New Journal of Chemistry, 2019

A new disulfide Schiff base as a versatile “OFF–ON–OFF” fluorescent–colorimetric chemosensor has ... more A new disulfide Schiff base as a versatile “OFF–ON–OFF” fluorescent–colorimetric chemosensor has been synthesized for sequential detection of CN− and Fe3+ ions.

Structural Chemistry, 2017

Vitamin C is known as an essential dietary supplement and implicated in diverse biological proces... more Vitamin C is known as an essential dietary supplement and implicated in diverse biological processes. We present here a theoretical study on the nature of hydrogen bonding of vitamin C in biological systems. For this reason, the complexes of vitamin C (VC) with neutral and zwitterionic Lalanine (as the simplest chiral amino acid) were studied at the MP2/6-311++G(d,p) level of theory. In the gas phase, neutral L-alanine leads to more stable complexes than the zwitterionic forms while the reverse is true in the aqueous phase. The complexes are formed via two hydrogen bond interactions, which result in a ring-like hydrogen-bonded networks. The nature of H-bonds was characterized in terms of natural bond orbital and quantum theory of atoms in molecule analyses (QTAIM). The H-bonds in the studied complexes were electrostatic in nature; however, in the case of shorter and directional H-bonds and ionic interactions, contributions of covalent character were also non-negligible. Natural energy decomposition analysis of hydrogen-bonded complexes reveals that the charge transfer and electrical components are the largest contributors for the interaction energies of complexes. Natural resonance theory analysis suggests higher resonance weight for charge-assisted interactions of vitamin Calanine (zwitterionic) complexes, where the total interaction energy is considerably higher than that of neutral alanine.

CrystEngComm, 2019

Four new copper(i) thiocyanate complexes were studied using geometrical parameters and the lump–h... more Four new copper(i) thiocyanate complexes were studied using geometrical parameters and the lump–hole approach for justification of the strength and nature of chalcogen bonding.

Applied Surface Science, 2018

In this work, the adsorption of cytosine (CYT) on the Au/Ag and Ag/Au bimetallic nanosurfaces has... more In this work, the adsorption of cytosine (CYT) on the Au/Ag and Ag/Au bimetallic nanosurfaces has been studied using density functional theory (DFT) in the scheme of the "our own n-layered integrated molecular orbital and molecular mechanics" (ONIOM) and compared with its adsorption on pure Au and Ag nanosurfaces, respectively. It was found the arrangement of Au and Ag layers on each other in the nanosurface has considerable effect on the adsorption energy (E ad), adsorption mode and the charge transfer between the CYT and nanosurface. The presence of Ag as sublayer in the Au/Ag nanosurface decreases the E ad of the CYT, increases the vertical distance of the CYT from the surface and changes its tilting direction from its oxygen atom to nitrogen atom of ring C=N compared to the adsorption of the CYT on pure Au nanosurface. The opposite trend has been seen for the adsorption of the CYT on the Ag/Au nanosurface which Au is as sublayer compared to the adsorption of the CYT on pure Ag surface. The tilting of the CYT from its oxygen atom on the Ag/Au nanosurface increases compared to that on pure Ag surface. Also, it has been shown that the Ag sublayers increase the charge transfer from the CYT to the Au/Ag nanosurface while the Au sublayers decrease the charge transfer from the CYT to the Ag/Au nanosurface, significantly. The quantum theory of atoms in molecules (QTAIM) has been also used to determine the interatomic interaction lines between the CYT and nanosurfaces to determine which atoms of the CYT and first layer of nanosurfaces are in local interactions with each other. The interaction energies of the CYT with the selected nanosurfaces have also been calculated at the Hartree-Fock (HF) level of theory and compared with those obtained using the DFT method to understand the reason of the change of E int due to the sublayers.

Journal of the Iranian Chemical Society, 2017

The [Co(5-XSalen)(PEt 3)(H 2 O)]ClO 4 (where Salen = bis(salicylaldehyde)1,2-ethylenediamine and ... more The [Co(5-XSalen)(PEt 3)(H 2 O)]ClO 4 (where Salen = bis(salicylaldehyde)1,2-ethylenediamine and X = H, MeO, NO 2 , Br) complexes were successfully synthesized and characterized by different techniques such as FT-IR, UV-Vis, 1 HNMR, 13 CNMR and 31 PNMR. The coordination geometry of the [Co(5-BrSalen)(PEt 3)(H 2 O)]ClO 4 complex was determined by X-ray crystallography. The complex has six-coordinated pseudo-octahedral geometry in which the O(1), O(2), N(1) and N(2) atoms of the Schiff base form the equatorial plane. The cyclovoltammetry was used to study the electrochemical properties of cobalt complexes, and the results reveal the anodic peak potential becomes more positive in order to MeO < H < Br < NO 2. DFT calculations were also done to investigate structures, electronic spectra and infrared spectra of the complexes. The synthesized complexes [Co(Salen)(PEt 3)(H 2 O)]ClO 4 , [Co(Salen)(PBu 3)(H 2 O)]ClO 4 and [Co(5-NO 2 Salen)(PEt 3)(H 2 O)]ClO 4 were incorporated within Montmorillonite-K10 (MMT) nanoclay. Furthermore, structural, thermal and morphological properties of the prepared nanohybrids were verified by FT-IR, XRD, TGA-DTG, EDX, SEM and TEM techniques. XRD results of the new nanohybrid materials elucidate that the Schiff base complexes were placed at the most outerlayer spaces of MMT clay.

Computational and Theoretical Chemistry, 2016

Abstract In the light of interacting quantum atoms (IQA) and natural energy decomposition analysi... more Abstract In the light of interacting quantum atoms (IQA) and natural energy decomposition analysis (NEDA) the nature of different types of beryllium bonds is studied. IQA intra-atomic (self) energies indicate that, in most of the traditional beryllium bonds (in which the Lewis base is a lone pair donor), π -Be bonds (Lewis base is an unsaturated molecule) and also the Be–Ng (noble gases) interactions, the beryllium atom is stabilized upon complex formations. According to IQA inter-atomic energy components, the Be ⋯ Y bonds (Y is an atom in the Be-bond acceptor that is connected directly to the beryllium atom) have a dominant classical electrostatic character. However, in the IQA partitioning of total inter-molecular interactions, the contributions of non-classical (exchange–correlation) terms are non-negligible. Natural energy decomposition analysis of traditional and π -Be bonds indicate that the attractive interactions come from both the electrical and charge transfer terms. The electrical term in the Be–Ng bonds is negligibly small and the charge transfer is the most dominant contributor in the interaction energy.

Applied Surface Science, 2017

In this work, the adsorption of DNA bases on the Cu(111) nanosurface was studied to investigate t... more In this work, the adsorption of DNA bases on the Cu(111) nanosurface was studied to investigate the electronic structure of the bases on the Cu surface and to find the effect of van der Waals interactions on the adsorption mode of the bases. The calculations were performed in the ONIOM scheme using two DFT functionals (PW91PW91 and wB97XD). It was found that using the long-range corrected DFT functional such as wB97XD (which considers the vdW interactions) decreases the tilt angle of the bases on the surface. The main molecular orbitals responsible for the interaction and charge transfer between each base and Cu surface were determined. The HOMO-4, (HOMO, HOMO-2, and HOMO-3), (LUMO, HOMO-3, HOMO-4, and HOMO-6), and (LUMO and HOMO-4) are responsible for the interaction and charge transfer with the surface for adenine, cytosine, guanine, and thymine, respectively. The quantum theory of atoms in molecule (QTAIM) was used for better characterization of the interaction of the bases with the surface by a topological analysis of the electron density. The results showed that the most interacting atom of adenine with the Cu surface is the N atom of the NH 2 group, whereas the most interacting atom of cytosine and guanine were the O atoms of the carbonyl groups. The QTAIM analysis also showed that the interaction of the O atom of cytosine with the Cu surface is stronger than that of guanine. For TY, the O and N atoms have higher interaction with the Cu surface compared to other atoms. Based on the calculated values of the electron density (BCP) and the positive sign of the Laplacian of the electron density (∇ 2 BCP) at the bond critical points of the atom-atom interactions, it was concluded that the interaction between the bases and the surface can be categorized as closed-shell interactions.

Computational and Theoretical Chemistry, 2017

Strain or electronic effects? MP2 and DFT aromaticity investigation in small ring annulated benzene

Phys. Chem. Chem. Phys., 2016

For the intramolecular hydrogen bond interplay in cooperativity, changes of the IQA atomic and in... more For the intramolecular hydrogen bond interplay in cooperativity, changes of the IQA atomic and interatomic interaction energies of the participant interactions were monitored during the formation of cooperative networks.

Journal of Molecular Structure: THEOCHEM, 2007

Electron density analysis within the framework of Quantum Theory of Atoms in Molecules (QTAIM) in... more Electron density analysis within the framework of Quantum Theory of Atoms in Molecules (QTAIM) indicates bond paths between oxygen atoms in open conformers of enol forms of cis-β-diketones. The calculation of atomic energies shows that such a OO interaction in 1, ...

Journal of Molecular Structure: THEOCHEM, 2006

In the current research, chemical nature of very strong hydrogen bonds in their three fundamental... more In the current research, chemical nature of very strong hydrogen bonds in their three fundamental cases, resonance assisted hydrogen bond [RAHB], negative charge assisted hydrogen bond [(K)CAHB], and positive charge assisted hydrogen bond [(C)CAHB] is studied. The results are obtained at B3LYP/6-311CCG** and MP2/6-311CCG** level of theories. Attention is focused on topological parameters such as electron density, its Laplacian, kinetic energy density, potential energy density and energy density at the bond critical points (BCP) of O/H and O-H bonds from Bader's atoms in molecules (AIM) theory. Charge transfer energies based on natural bond orbital (NBO) analysis are also considered. Our results show that these hydrogen bonds are partially electrostatic and partially covalent in nature, in which the covalent contribution increases as the stabilization energy of hydrogen bond increases. In addition, it is shown that, as the O-H-O angle in intramolecular hydrogen bonds approaches to 1808, the charge transfer energy from oxygen lone pairs to antibonding NBO of O-H increases. In the investigated systems, double minimum no barrier (DM/NB) potential energy surface (PES) is obtained for hydrogen transfer between the two oxygens. AIM analysis based on DFT calculation for the transition states (TSs) show that the hydrogen atom is connected to the oxygens with two almost identical covalent bonds with some contribution of electrostatic interaction, while MP2 calculation predict two covalent O-H bonds in some cases.